A power seat-adjusting mechanism is normally provided both to vertically displace the front driver's seat of an automotive vehicle as well as to displace it in the direction of travel so as to accommodate drivers of different height. In addition from a comfort point of view it is frequently considered desirable to be able to change the front-to-back inclination of the seat.
These functions were originally done by the expedient of providing several small motors working through respective gear drives to carry out the various functions. Obviously such an arrangement is relatively expensive and quite complex. Furthermore such an arrangement takes up a great deal of space under the seat and does not lend itself to inexpensive serial production.
It is therefore been suggested, as in U.S. Pat. No. 3,079,118 of J. Pickles, to provide a single drive motor which can be connected via various solenoid-operated clutches to several different gear trains which carry out the various functions. This type of arrangement does, indeed, represent a substantial saving in expensive mechanism. Nonetheless it still is rather cumbersome and failure prone.